Liquid crystal displays have been widely used due to their excellent quality. However, as liquid crystal itself emits no light, a backlight module is required to provide light necessary for displaying images. In order to guarantee a good effect when viewed from all angles, liquid crystal display screens have to meet the requirement of uniform brightness. It is thus required that the brightness of the emitted light from the backlight module must be uniform.
Side entering type backlight modules have been the mainstream of design of backlight modules. However, for a side entering type backlight module, as shown in FIG. 1, a light bar 2 has a plurality of point light sources, for example, LED (Light Emitting Diode) lamps 3 (approximate to point light sources). The space between adjacent LED lamps 3 is A, and the distance from light emitting surfaces of the LED lamps to light incident surface 12 of a light guide plate 1 is B. As the LED lamps 3 have a certain light emitting angle α, a region 4 (i.e., hot spot, also referred to as glow-worm effect) not covered by the emitted light of the light bar, is generated in the marginal portion 11 of the light guide plate. Due to low brightness of the hot spot, the brightness of the emitted light from the backlight module is caused to be non-uniform. In general, the larger A is, and the smaller B is, thus the phenomenon that the brightness of emitted light from the backlight module is not uniform is more prominent.
The inventor(s) found that the prior art at least has the following problems. With the continuous increase of the luminous efficiency and power of the LED lamps, the number of LED lamps required by a single light guide plate is reduced, and the space A between lamps is continuously increased. As a result, the hot spot becomes an increasingly serious problem, which is disadvantageous to border narrowing of the backlight modules, and also adversely affects the display quality of the display devices. In addition, if the brightness problem of the hot spot cannot be solved well, it is unable to introduce LED lamps of greater luminous efficiency and power, and then it is disadvantageous to reduction of the production cost of products.